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SubjectPossible memory leak in request_firmware()
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Hi,

I get a couple kmemleak reports like below which I think happen on the
failure path (-ENOENT) of a request_firmware() call:

unreferenced object 0xc355fdb0 (size 256):
comm "NetworkManager", pid 2606, jiffies 4294902882
backtrace:
[<c01e0c3a>] create_object+0xfa/0x250
[<c01e1e7d>] kmemleak_alloc+0x5d/0x70
[<c01dac1b>] kmem_cache_alloc+0x14b/0x190
[<c03a0c4c>] _request_firmware+0x11c/0x530
[<c03a1102>] request_firmware+0x12/0x20
[<f95f6591>] iwl_mac_start+0xa1/0x850 [iwlagn]
[<f8fb08c1>] ieee80211_open+0x2e1/0x860 [mac80211]
[<c048459a>] dev_open+0xba/0x100
[<c0483ab9>] dev_change_flags+0x139/0x1d0
[<c048d392>] do_setlink+0x282/0x410
[<c048ea81>] rtnl_setlink+0xf1/0x130
[<c048e285>] rtnetlink_rcv_msg+0x165/0x200
[<c049fac6>] netlink_rcv_skb+0x76/0xa0
[<c048e10e>] rtnetlink_rcv+0x1e/0x30
[<c049f7fb>] netlink_unicast+0x23b/0x250
[<c04a02db>] netlink_sendmsg+0x1db/0x2d0

The f_dev in _request_firmware() is allocated via the fw_setup_device()
and fw_register_device() calls and its class set to firmware_class (the
class release function is fw_dev_release).

Commit 6acf70f078ca replaced the kfree(dev) in fw_dev_release() with a
put_device() call but my understanding is that the release function is
called via put_device -> kobject_put -> kref_put -> koject_release etc.
and it should call kfree since it's the last to see this device
structure alive.

Because of that, the _request_firmware() function on its -ENOENT error
path only calls device_unregister(f_dev) which would eventually call
fw_dev_release() but there is no kfree (the subsequent put_device call
would just make the kref negative).

The patch below may fix the problem but it's only later tonight that I
can test it and confirm:


diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index ddeb819..12e6e64 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -357,7 +357,7 @@ static void fw_dev_release(struct device *dev)
kfree(fw_priv->pages);
kfree(fw_priv->fw_id);
kfree(fw_priv);
- put_device(dev);
+ kfree(dev);

module_put(THIS_MODULE);
}
@@ -407,14 +407,13 @@ static int fw_register_device(struct device **dev_p, const char *fw_name,
retval = device_register(f_dev);
if (retval) {
dev_err(device, "%s: device_register failed\n", __func__);
+ kfree(fw_priv->fw_id);
put_device(f_dev);
- goto error_kfree_fw_id;
+ return retval;
}
*dev_p = f_dev;
return 0;

-error_kfree_fw_id:
- kfree(fw_priv->fw_id);
error_kfree:
kfree(f_dev);
kfree(fw_priv);

--
Catalin



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